The corresponding dose-response curves resulted in a higher EC50 for prostatospheres than for control adherent cultures with both drugs (3.06 vs. 2.13 μM for daunorubicin and 20 vs. 9.27 nM for topotecan), showing that CSCs are significant more resistant than other cancer cells to ABCG2 transported drugs. The gene discussed is ABCG2; the disease is cancer.